Lathe chuck



April 2s, 1925.

F. C. SMART LATHE CHUCK Filed Nov. 18, 1919 2 Sheets-Sheet l fri zlm w Q/ f 3 3 Bc. A ef -..l i- .-wl -z l, mi. \s, n y L M 2 X April 28, 1925v vF. CC SMART LATHE CHUCK Filed Nov. 18, 1919 2 Sheets-Sheet 2 T all whom jz'z may concern.'

Patented Apr. v2S, k1925. y

UNITED STATES PATENT OFFICE.

' FRANK C. SMART, 0F HARTFORD, CONNECTICUT.

LATHE CHUCK.y

Application lled November 18, 1919. `Seria1 No. 338,801.

,Be it known that I, FRANK SMART, a citizen. of the United States, residing in Hartfordin `the countyl of Hartford and State oit' Connecticut, have.inventedcertain new anduseful Improvements .in Lathe Chucks, of which cation.4 y v This .invention relates to the class of lathe chucks, a formlof which is illustrated and the following is a specifidescribed in my Patent No. 1,325,915, issued Dec. 23, 1919, to which referencemay be had.

An object of myA present inventionv is to furnislran improved ,construction and organization of the jaw-operating screws and screws-holding bearings yfor use in the class of lathe chucks which is provided with a series otradially disposed and slidable workholding .y jaws. Chucks of this class are sometimes made ,with'two or with three jaws,

these being,` evenly spaced apart in the circumference of the chuck-body, but more generally the chuck aws are four in number.

. A further object of my present invention `is to furnish a chuck in l,which the body `portionofthe chuck is provided at an edge `thereof withmeans coactive with means arranged vat yan edge of ring segments or bearing segments of the bearing-carrier or ring for positively preventing the ring segments or bearing segments from being moved upwardly; in the presentinstance this object @being accomplished by means of a groove formed in an edge of the body portion of the .chuclaand a rim formed .in an edge of each ring segment or bearing segment which engageswith said groove. l

Another object-is ito furnish a chuck provided'withjmeans engaging thebody portion v,of the chuck andengaging the ring segimentsy or `bearing segments vof the bearing carrier or ringfor subjecting `the bearing `carrier vror. ring to a powerful contractile force or pressure, this object in the present yinstance being accomplishedby means of wedgingv members which vengage the body portion, andthe ring segments or bearing segments ofthe bearing carrier or ring.

Further objects are hereinafter stated and explained. ,y -f y o In the particular varietyof chuck selected for illustration herein, the jaws are shown of a conventionalform and arefour in number, :and they are preferably.radially-disposedin the usualmanner illustrated; but,

it is to be understoodthat theterm radiallydisposed7 and other termsof similar import as kused herein, are not. to be strictly construed, and that they refer merely to the general or approximate arrangement, and do' not require or imply an exactly radial positioning of any part or parts so designated.

In the accompanying drawings forming a part of this specification, Figure 1 is a plan view, (in this special art, also sometimes designated as a ront7 view), of a lathe chuck of the class to which my present improvements are especiallyv applicable; in this view, one portion is broken away for more clearly illustrating certain details.

Fig. 2 is a sectional view `on the line )i2-X2 of Fig. 1, showing theparts above said line as seen from below, butwith the jaw D2 and screw Sshown in side View, and ywith ,the screw S4 shownonly partially in section. i

Figure 3 is a plan View illustrativeof the ring-and-bearing `system which is of composite construction.

Figure 4 is a sectional view on the; line U-Xt of Fig. 3, `showin-g theparts above operating screws. 5 i

Figure `8 isa fragmentary sectional View for illustrating an initialstage of the assembling operation, as hereinafter more fully explained. y y

Figure 9 illustrates a means for contractivelyholding the bearing carrier or ring.

Similar characters designate like parts in all of the views. 1 i u i Referring to the drawings,in Figs. 1,y 2, 3,.thechuckbody member, B, is shown of y,a common form, excepting as to certain features in connection withV the screw-holding bearings, as hereinafter explained.v Said member B has formed therein a series of slots or guide-wa s, as C, (Fig. 1), which are or may be racially-disposed, and which are fitted with ribs and grooves coactive with ycorrespondingf'yfeatu'res -rof the jaws D, respectively.'l The vguide-'ways C are "eX- tended downwardly, and are shaped'atthe bottom thereof, to form the Jguide-,ways

for the jaw-operating screws S, respectively.

In the present instance, the body member B is shown as having only a single pan' of ribs, as 2, 2b,'Fig. V2',jwhich engage in a` corresponding pair of grooves, as en, 4L", of the jaw 1D, so that this aw isshda'ble on *and guided v.by the ribs oi the body-member in va well-known' manner.

Thus the jaw D is shown herein as having formed in each sidethereof, only a single groove,"`as4", or 4,"b`ut in some 1nstances,--andaccording to a.commonpract1ce,-a plurality of such coacting ribs and grooves (not y:herein shown) may be prov1ded,-1n a well-known 1nanner,-on'eacl 1 side `of any oneor vmore of the aws.

Q ,The 'several vchuck-jaws are herein rey ferred to asfjaws D, andvr jindividually without'choice as jaw D, but for c'onven# n iencey or ijeferencefeespecially in `comp'arf ing RJ the drawings,-the vfour jaws" D are hereinAv separately indicated'by the charac# tersDDBfD', and D?, respectively. Similai-ly, the `four jawsactu'atingscrews S,

b'utare separately ``indicated by the "cha-racters" SSlf", S, and S5, respectively.' This notationmethod is alsoapplied herein to u, 4the guide-ways C and E, lfor the D and screws, respectively,also,l tov the screwholding bearings H, 'hereinafter described. The'jawsD are' herein shown as `being duplicates and also of a common reversible `io'rm, 'and as engaging (by a segmental nut integral ywith the j aw) in a well-known manner with the `screw thread, ast, of the du'- plicate screws S, respectively; f.

The chuck-jaws, D', are `usually provided with three or more work-holding faces, but

i only three 'such faces Iare herein Ishow-n.

Two of these `faces, 4C, `and 4d, are` shown formedin a' usualfmannernon the ends 'of the jaw, wh1le ak thirdy said -face, 4e, yislocated (also in a 1usual manner) at `some convenient or desired position intermediate, to

[reversed 'f Since; the class of chucks kherein illustrated are especially adapted and intended for uSewhenattacliedtothe' spindle of a lathe or analogous machine,-it is customaryto form on the Vback ofthe body member,'B, a face, as 2k, and a holding'rim, asQ", for

receiving a' flanged'hub, "which maybe of 'the "customary or general form and which,

in y`:uicordan'ce with a comitfon practice; may

be removably fixed to, or mayfb'e made in-V tegral with such a machine spindle.` Hence itis als);customary` to malte throu h said member B, a series of holes, as 2g, `ig. 1),

fora plurality of ordinaryl hub-holding bolts (not herein shown), by which to removably attach the chuck body to the flanged hub in a well-known*manner.` Necessarily, said bolt-holes 2 are located inthe spaces between the jaws D, as shown in Fig. l, sothat said holes extend through'the thickest portions of the castingsofwhih the chuclilbodies, as B, arenanufactndd,

andthe utility and economy of mypresent invention relative to blow holes inthe"y body B, incident to providing holessuch` as 2g in the body B, are the same as set forth in my patent-before mentioned. A

Having in view .the "general eatnres of 1 the chuck as alread set forth, it `willfbe seen by comparing figs-1,2, and j\7,`1that the thread, t, of screWS is cbntinuousind uninterrupted through its length and, that `on their inner ends, the screws S are f "rolonged in the yform of "a `Journal, 7,;w `ich is provided with one `or more rib-like rings `that are in the nature "of thrust-bearings or thrust collars. In thepresent instance, thse collars',17, are shownthreein number, and in external diameter they may correspond with' but shouldvv not loe-greater thanthe y diameter of the body4 jaws D mayipass'over said collarsjlin the 'usual manner, without inter-ferencdas will be evident from Fig. V2. Saidjournallends,

portion 7"of the screw S, inside ofthe thread It, so that' the 7, are `shown fitted to turn inbearinyH,

which are fitted into the guide-Ways spectively, and areflccated and secure 'in position f at the eXtreme inner lends of `these guide-ways,``see Figs. l, 2, Tand 6p-and are therein maintained preferably the `means and in thev manner hereinafter-more fully explained. n

For` engaging the screw S with then-.bearings Heach said bearing is shown having fo-rmedtherein one or more semifciiclar Thus, when the bearingsare Ithrust-bearing channels'or grooves,`.as8,-` v,each having a pair of thrust-faces, as 8', and 8h, Fig. 6, (corresponding with said 't`h` 1"ustu collars 7a).

in place, `the screws S may `bellaid`down wardly into their @guide-WaysE, and n thus place :the 'said annular` thrust-bearing frings `or journals'7a,.insaid semi-annular "thrustbearing' channels '8, respectively;` next, `the jaws D maybe slid into theirreceivingchan nels C` by engaging the usual jaw-"guiding ribs, or ways,\2a, Q", of thebody B in the guide-channels 4, 4, respectively, of the Jaws. During this part ofthe assembling operation, ot course, the segmental-nut threads t2, ofthe jaws will'beyengaged with i the threads t of thev screws' S,respectively` so that by turning a screw S, the `coacting jaw may be slid along on itsguides to any required'position within the normal work ing range thereof; In Fig. 2, the screw St s ment also operates to normally hold the in' ner end portion of the ournal 7 of the screw S downward into the bearing H, so that said thrust-collars Ta'are maintained in proper engagement with said semi-a`nnular thrust facesrSa, 8b; However, should a jaw D be removed, (as will be required at times in using the chuck), the coacting-screw S would be released' and might fall out. To prevent such av displacement, and also to assist in retaining screw S in placewhen the yjaw D is drawn out to an extreme position, I have provided the screw-retaining ring P which is in the nature of a bearing cap, and; which may be removably secured in place in` any convenient manner, as for instance, by a series of small cap-screws, as 9, of suitable number and arrangement. i n w The several screw-engaging bearings, as H2, H3, H4, and H5, are herein shownin Fig. 2, as being each integrally joinedto the immediately adjacent (the contiguous) portion ofthe bearing-carrienor ring, N. Thus each ofthe bearings H may be said, when considered as an entirety, to comprise `a bearing proper, as H, which is fitted to lie down firmly in said guide-way E for the screw S, and also to comprise an anchor bearing, which, (in said construction of Fig. 6), consists of asegmentalportion lof the ring N, as, forinstance, the portion between the dotted lines gf, y', `(Fig. 6),and there designated byf/fThe proper tensioning or tensely-iXing in place of the bearing H may be-accomplished in practice as indicated in Figs. 2 and 8, wherea section of the yring N and of a bearing H, is shown in position for beginning `the forcing-in operation, this being indicated by the arrow T10; `in said Fig. 8, of course, the differences of diameter of the surfaces 8f vand 2f are indicated as being very much enlarged in order tosecure clearness of illustration; in practice,.in the manufacture of any particular size of chuck, the proper amount of said difference in the diameter of the faces 2f and 8f., are readily ascertained by trial.

l One object accomplished by thesystem or organization herein set forth, is the subjection of the screw-holding bearings toman ring.

initial positioning stress or tensioning with relation to the chuck-body and relative to each other, vprior to the application thereto of any work-holding strain. Accordingly, when such a strain is applied, as indicated in Fig. 5, by the arrow T5, the force so eX# erted by the work as WV, against the jaw D is transmitted through the screw S and thence through the pair (or pairs) of engaging and coacting screw and bearing faces, to the anchor-bearing, H, with the result of applying to this bearing an outwardly acting force in the direction of the arrow r3, this direction being the same as that of the said previously-produced initial tension. Thus, on the work-holding strain being gradually applied,-as necessarily occursin practice, by the operator turning the jaw-actuating screw S,-the force thereof is increasingly transmitted through the described faces and is finally resisted by the face `22m the direction of the arrow r2; hence, as will now be evident, the newly ap-` plied work-holding strain will be supported by the pressure of abutting faces which were already underthe pressure of forces acting in the same direction.

`In Figs. l and 3, the composite and continuous construction of the carrier member is shown. In these views, the bearings H2, H3, H2, H5, are shown as each integrally ioining with a segmental member, as N2, N3, N4, N5, respectively,each forming one portionof the complete but composite carrier Thus each said bearing corresponds with the bearing and ring-segment shown in Fig. 6 and consists of the bearing proper, as H, and an anchorage flange,-here designatedfas a ringsegment,-having anzouter face, 8f, for engaging within the aforesaid inner `face of the body portion of the chuck, forming the compression hoop within which said carrier is held under a contractile stress. )When the bearings H, are four in number, the arcual length of the bearing-flange or segment, as h2, (Fig. 3), may be made considerably less `than ninety degrees, and thereby provide for a series of tensioning, or straining-up members, as T2, T2, T4, T5, which, as clearlyindicated in the drawing, (Figt) may be of a slightly tapering form, so as to act as wedges when forced firmly `into place bet-ween said bearing members.

The` wedge members or straining-up members T2, T, T4 and 4T5 when properly forced between adjacent ring segments N2, exert a pressure or for-ce upon the portions of the ring segments with which such members abut, as indicated by the arrow t, Fig. 3, and as will readily be understood.

This system of assemblage,-Figs. 3, 4,- provides Afor a further improvement. In FigfS, an annular recess, 2m, is formed in the body zone B', at the lower edge of the face 2f, and the lower edge of each of the ring-segments, as N2, etc., is provided with ya rim 8m which. locks into said recess, thereby positively preventing the bearing `segment from being moved upwardly. `Infassembling this form of the ehuck,the several bearings H, are dropped into place in .their seats, E, 'and are then slid outwardly until their ring segments bear against the body face 2f, while the rims, 8m, are engaged in said recess 2m; these groove-faces, or segment-faces, whereby the members engage for locating them, are shown as being in planes which are transverse to the `axis of the chuck. Next, the wedge members, T, are forcibly-pushed down between said ring-segments, for thereby locking the several parts into a firmly fixed assemblage, and subjecting. the entire ring,-by suchexpansion thereof,-to la powerful contractile force within the body-zone, or hoop, B. i

In this construction it will be seen that the views 2,4, 5, 6 andS differ from the specific forms shown in said origi-nal patent merely by 'the omissioncof an immaterial shoulder at the junction of the ring N and the bearing segment II. The groove shown in said patent along the upper edge of theclutch body B (at the upper edge ofthe face 2f) is also herein omitted, it being immaterial to the subject matterhereof. -4

In the :modified formwhich is illustrated in Fig. 9, the bearings H are integrally'connected withthe carrier ring N, in the same manner as already described in my above mentioned patent but a different-means iis provided for subjecting the` bearing carrier ring to contractilepressure'within the face 2V of the body B.; f

The said inner face of the body member is formed slightly conical, as 2f', the larger di.- ameter being adjacent to the face 2k. of said member. Also, the louter face of thering N, which ring is integral throughout the entire circuit, is of a conical form, 8f', :the direction of the inclination, as seen in a sectional view being in thev same direct-ion as said face'2f, but, preferably, slightly divergent'` therefrom, as indicated for instance by the dotted line y?, g8. The ring N being inserted in the central opening of the body member B, with the bearings I'Ivproperly located in their respectiveseats, E, `then a wedge ring, 12, is inserted between saidfaces 2f. and 8f', and is then pushed into place for thereby locking,

as by a key, said bearing-carrier firmly in place within the member B, said keying-in ring being ineffecta portion of thev bodymember B. In practice, and in order not to require an upsetting (circumferentially thereof), of said keying-in ring 12, this keying ring may be divided at one'or 'more 'points (not shown), so `as to facilitate the necessary contraction in diameter while being forced into place. v v

In the arrangement here described, and by suitably :proportioning the several parts, that portion of the ring il which lies in the lower zone z5, may `be-forcibly compressed in diameter for. thereby securing the desired tensityv in `the positioning of the bearings H.

kAt the 4same-time said keying-in member`12 operates,-in an evident manner,--to very securely and rigidly lock theimember N `and bearings H accurately in position. j .i

F rom the foregoing description it will now beev-ident how the surface of the semicylindrical, or partly-cylindrical guide-Way E, is used in part as abearing-surface `for the screw S and also in part as a supporting seat, face, or surface for receivinmthereon the semi-annular, or partly-annular,` bearing H. VAlso, how the same guide-surface E of a body B, may be used to support `bearings H having different lengths, respectively. For use in a chuck-body `of some given size and proportion, in one instance, a ri `N having short bearings H may be secure 1 in the central position, Aand in another-instance, a ring N having much longer bearings H, may be secured in said position, Thus, `one and the same portion (adjacent toybearing H)l of the same face of a guide-wayEfj this face being continuous, uniform and iunbroken, may in one instance constitute in partthe bearing-surface for a screw S, and inanother instance yconstitute ,a supporting face for a` thrust-bearingH.`

Having thus described my y invention, I claim:

y 1. Iny a chuck, -in` combination, a bodymember; a seriesxof thrust bearings; jawactuating screws operative in saidbodyn memberprovided with means forengaging said thrust bearings; workrengaging jaws vlocated in said body-member and `actuatable by said screws; and wedging means` for` exerting Vaxialpressure on said thrust bean ings. e. i2.. .Inv achuck, in combination, a bodymember; segments provided with thrust bearings; jaw actuating screws operativelin said body-member provided with means for engaging said thrust bearings; work-engag ing jaws located in saidvbody-member and actuatable. by said screws; and iwedgin .means for exerting axial pressure on sai .thrust bearings. j 3. In a chuck, in combination, abodymember; ring segments, each segment being provided with thrust bearings; jawactuat-ing' screws operative in seid bodymember provided with means for engaging saidthrust-bearings; work engaging jaws located inthe body-member and actuetable by said screws; and wedging means for from said opening; ring segments aiianged adjacent to said guide-ways, each segment being providedv with thrust-bearings; jawactuating screws operative in said guideways and provided with means Jforengaging said thrust-bearings; work-engaging jaws located in said opening` andactuatable by said screws; and wedging means for exert'- ing axial pressure on saidy thrust bearings.

5. In a chuck, in combination, a bodyinember having a mid-space openingv and having guide-ways extendingkradially outward from said opening; ring segments arrangedbetween 'said guide-ways, each segment vbeing provided with thrust bearings; jaw-actuating screws operative in j said guide-ways*andV provided with means for engaging said thrust bearings; work-engaging jaws located in saidopening and actuatable by said screws; and wedges between the ring segments for exerting axial pressure on said thrust bearings.

6. In a chuck, in combination, a bodymeinber; a series of thrust bearings; jawactuating screws operative in said body-- `member provided with means for engaging said thrust bearings work-engaging jaws located in said body-member and actuatable by said screws; wedging means vfor exerting axial pressure on said thrust bearings; and -means for preventing" movement of the thrustbearings axially of the body-meinber.

'7.' In a chuck, in combination, a bodymember; a series of thrust bearings; jawactuating screws operative in said bodymemberprovided with means for engaging said thrust bearings; work-engaging jaws located in said body-member and actuatable by said screws; wedging means for exerting axial pressure on said thrustvbearings; and means coactive between the thrust'bearings and the body-member for preventing move- ,mentf'fotfthe thrust bearings axially of the body-member.

8. Inla chuck,` in combination, abodymember; segments, each segment being provided with thrust bearings; jaw-actuating screws operative in said body-member provided with means or engaging said thrust bearings; work-engaging-jaws located in said body-member and actuatable by said screws; and wedging means coactive between the segments for exerting axial pressure on said thrust bearings; 'said segments `being provided with means for engaging the bodymember for preventing movement of the segments axiallyot the body-member.

9. Iii a chuck, in combination, a bodymember; ring segments, each segment being provided with thrust-bearings; jaw-actuating screws in said body-member and provided with means Jfor engaging said thrust bearings; work-engaging jaws located in the body-member and actuatable by said screws; and wedges between the ring segments for llocated in said opening and actuatable by said screws; and wedges between the ring segments for exerting axial pressure on said thrust bearings; `said ring segments beingV provided with means on the ring segments for engaging means on the body-member for preventing movement ot the ring segments axially of the body-member.

ll. In a chuck, in combination, a bodymember; a series of annular grooved thrust bearings; jaw-actuating screwsoperative in said body-member and provided with annular collars tor-engaging said thrust bearings; work-engaging jaws `located in said body-member and actuatable by said screws; and wedging means for 'exerting axial pressure on said thrust bearings.

V12.'In a chuck, in combination, a bodymember; segments, each segment being provided with annular grooved thrust bearings; j aw-actuating screws operative in said bodymember and provided withannular collars for engaging said thrust bearings; workengaging jaws located in said body-member and actuatable by said screws; and` wedging means for exerting axial pressure on said thrust bearings.

13. In a chuck, `in combination, a bodymember; ring segments, each segment being provided with annular grooved thrust bearings; jaw-actuating screws operative in said body-meinber and provided with annular collars for engaging saidthrust bearings; `work-engaging 'jaws locatedy in said bodymember and actuatable by said screws; and wedges between the ring segments for exerting axial pressure on said thrust bearings.-

14. In a chuck-fin combination, a bodymember; a seriesfotannular giooved thrust bearings; jaw-actuating screws operative in said body-member provided with annular collars forengaging said thrust bearings; work-engaging jaws locatedl in vsaid bodymember and yactuatable byv4 said screws; wedgingnieans coactive between said thrust `bearings for exerting axialpressure on said f thrust bearings; and means for preventing movement `of the thrust bearmgsaxially o-i the body-member.

15. In a chuck, `in combination, a bodymember; segments, each segment being provided' with annular' grooved thrust bearings; jaw-,actuating screws operative in said body-member and provided "with annular collars for engaging said thrust bearings; work-engaging jaws loc-ated in said bodymember and actuatable by said screws; wedging means coactive between said segments for exerting axial pressure on saidy thrust bearings; and means for preventing movement oi' the segmentsaxially of the body-member. v Y j f 16. Inra cl1uck,in combination, a'rbodymember; ring segments, each ring segment being provided with annular grooved thrust bearings; jaw-actuating screws operative in.

member fork preventing movement of the ring `segments axiall;7 of the body-member.

1T. In a chuck,` in combination, a bodymember having a mid-spacefopening and having guide-ways extending outwardly trom said opening; ring segments arranged between said guide-ways, each ring segment being provided with annular grooved `thrust bearings; j aw-actuating serewsoperative in said guide-ways and provided with annular collars for engaging said thrust bearings; wor z-engaging j aws located in said opening and actuatable by said screws;` and wedges between said ring segments for exerting axial pressure on said thrust bearings; said ring segments being provided with-a rim for engaging a grooi'e in the body-member for preventing movement ofthe ring segments axially of the body-member.l j

18. Inra chuck, in combination, a bodymember having a mid-spacefopening and having guide-ways extending outwardly i'rom said opening; ring segments arranged between said guide-ways, each ring segment being pirovided'with annulargrooved thrust bearings j aw-actuating screws operative i in said guide-ways and provided withannular `collars for engaging said thrust bea-rings;

work-engaging jaws located in said opening and actuatable by' said screws; and Wedges between said ring segments for exerting axial pressure on said thrust bear-l ings; said ring segments being composediof a thrust bearing portion and an anchorage portion for engaging the body-member, and the anchorage portion being provided with 4a rim for engaging a groove inthe bodymember. 1 i 1.

19. In a chuck,` in combination, a bodymember having a mid-space opening and having guide-ways extending outwardlyy ing lscrews operative in .said guide-Ways, s

each screw being provided 'withannlilarcollars for engaging said thrust bearings and a .journal for engaging said journal bearing; means forretaining the journalsof the jaw actuating] screws in enga-gement with the journal bearings of i the ring segments; work-engaging ljaws located in said opening and actuatable bysaid screws; and wedges between said ring segmentation` exerting axial pressurefon said thrust bearings; said ring` segments being composed of raithrust. bearing portion and an anchorage portion for engaging the body-member, (andA the anchorage portion being provided witha `rim forengaging a groove in the body-member.

20. In a chuck` in combination, a bodymember having a mid-space opening and having guide-ways extending radial-ly ont- .ward from said opening;ring segmentsar-` ranged between said guide-ways, each ring segment being provided., ,with annular groovedthrust bearings and ajournal bearing; jaw-actuating screws operative in said guide-ways, each screw' beingprovided with annular collars for; engagingy said thrust bearings and a journal for engagin said journal bearing; meansfor releasab y retaining tlie journals of the jaw-actuating screws in engagement with the journalibearings .of the ring-segments; wedges between said ring segments for exerting, axial `pressure on-said thrust bearings; and means for actuating the jaw-engaging screws toacime` ate the work-engaging jaws; said ringsegments being composed `of a thrust `bexn'ing *l portion andan anchorage portionyfor `engaging the body-member; `and the anchorage portion being provided with a rimfory en` gaging a groove in the body-membern j j 21a. As,` an. article of' manufacture, `the herein `described chuck-screw bearing con;-

sisting of aringsegment having'segmenty yracesin planes transverse tothe axisofa lathe chuckforye1igagement with thebdy portion. of a lathe chuck. the ringsegment having wedge `races positioned `forengaging similar ring segments and forming with `said segments a continuousring for receptioni in i the axialborefof a lathe"cliuck,andibing jjyrovided withan anchorage portion for ene gaging the body of alathe' chuck having` vmeans tor preventing movement of the ring segment axially of the Y bore of the chuck when so engaged. i f

lVitiiesses: i i j i `h/IARGAnn'r R; DAVIDSON, ANNA lPIGKEL.` f

FRANK sMARTf i 

